Automatic path selection for fiber-optic transmission networks

Details Automatic path selection for fiber-optic transmission networks Automatic path selection for fiber-optic transmission networks

1997-04-15

2001-03-20

Nguyen, Chau (Department: 2663)

Multiplex communications

Channel assignment techniques

Using time slots

C370S468000

Reexamination Certificate

active

06205154

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the field of telecommunication systems, and more particularly to automatic path selection for fiber-optic transmission systems.
BACKGROUND OF THE INVENTION
Existing fiber-optic communications networks are typically based on a time-sharing technique whereby time slots in a time frame are assigned to different terminals that generate communications traffic. A great many network protocols for time-sharing within such networks have been disclosed in the prior art, where these protocols are known as time division multiple access (“TDMA”) protocols.
One standard implementation of the TDMA approach used in fiber-optic based networks is known as SONET (“Synchronous Optical Network”). SONET uses a simple time multiplexing technique to accommodate increasing numbers of SONET terminals and provides the flexibility needed to transport many digital signals with different capacities.
A major drawback of current systems utilizing SONET transmission facilities is that the user is required to manually enter or specify which time slots are to be used for a requested service. For example, system users may use a GUI (“Graphical User Interface”) to specify to an EMS (“Element Management System”) which time slots are to be used for the desired service. If, for example, a system user wishes to provision a T1 service between two nodes of a SONET network, the user must enter the time slots (e.g., STS number, VT group, and VT1.5 identifications) into the system so that the system can cross connect the time slots through each node, thus providing the requested path. Additionally, the user must provision T1 ports at each node so that the system may command the network elements to drop the selected time slots at the desired ports. In addition to the disadvantage of manual entry, this approach results in the inefficient utilization and fragmentation of the available bandwidth, as the users are not aware of which time slots are unoccupied in the STS channels and will use whatever time slot they are accustomed to use or is immediately available.
Accordingly, there is a need to provide an automatic system and supporting methods, both being selectively engageable to assign time slots within fiber-optic TDM transmission networks to various services in accordance with a predetermined scheme such that the system provides automatic path selection to the users, avoids bandwidth fragmentation, and optimal bandwidth utilization.
SUMMARY OF THE INVENTION
In accordance with the present invention, a system and method is described which provides users with automatic path selection capability, where time slots within SONET facilities are automatically assigned utilizing a predesigned selection criteria in response to a communications service request. When a user has requested the system to assign an end-to-end path through the SONET network, the system will use the methodology of the present invention to automatically select the time slots that will be needed to cross-connect through each optical facility to provide an end-to-end path which optimizes available bandwidth. The present invention thus provides a significant enhancement over the manual entry method of prior art systems.
In one embodiment of the present invention system, the user specifies the facility level to be provisioned (e.g., a T1, T3, or STS-3c service), and the identification of the add/drop nodes, which is where traffic is entered on and off the network. Based upon this input, the system will then select using a two-fold slot selection process, the time slots within each intemodal optical facility and cross-connect those time slots at each node via message sequences, thus providing automatic end-to-end path selection.
The present invention method solves bandwidth fragmentation and optimizes bandwidth utilization by selecting a time slot which maximizes the remaining bandwidth with respect to a future T1, T3 or STS-3c service request. For example, as STS-1 time slots become unavailable by assigning their bandwidth to specific services, a next VT1.5 time slot to be assigned for a T1 service request would be that in the most fully assigned or occupied STS-1 time slot which has the required availability. If a new unoccupied STS-1 time slot is required or the service request is for a T3 or a STS-3c service, then the system selects an unoccupied STS-1 time slot with reference to the number of contiguous unoccupied STS-1 time slots in the system. These time slot selection criteria assure that the available bandwidth is assigned in an efficient and systematic manner so as to avoid unusable or fragmented time slots.


REFERENCES:
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patent: 5345446 (1994-09-01), Hiller et al.
patent: 5351236 (1994-09-01), Pawelski
patent: 5412652 (1995-05-01), Lu
patent: 5546400 (1996-08-01), Hironaka

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